To be perfectly honest with you, I believe “time management” and “being productive” are extremely vague and, therefore, meaningless expressions. They certainly shouldn't be what we aspire towards or make our focus.

You're a software developer. You don't want to be productive. You want to build software (given the context of your occupation). “Being productive” isn't a vivid image or a specific target. Building feature X, on the other hand, or writing the CSS for the login page is clearer. You know what it involves and looks like.

Rather than ask yourself whether you're being productive or not, ask yourself more specific questions about your work and what you intend to do. If you were to re-write the “Why will this be any different?” section with specific projects/activities for each list item, what would they be? You don't have to share them over here, but I think you'll find it much easier dealing with tangibles than aiming to “be productive.”